// 判断是否为全屏
/**
 * [isFullscreen 判断浏览器是否全屏]
 * @return [全屏则返回当前调用全屏的元素,不全屏返回false]
 */
export function isFullscreen() {
    return (
      document.fullscreenElement ||
      document.msFullscreenElement ||
      document.mozFullScreenElement ||
      document.webkitFullscreenElement ||
      false
    );
  }